Physics CP02 Motion and Forces

• What is the term used to describe the force that results from the combination of two or more forces?

  Resultant force
• What is the difference between scalar and vector quantities?

  Scalars have magnitude only, while vectors have both magnitude and direction
• What is a scalar quantity mentioned in the study material?

  Speed
• How does the resultant force affect an object moving at a constant speed?

  The resultant force is zero when an object moves at a constant speed
• If a cyclist is pedaling with a force of 30 N and friction is 10 N, what is the resultant force?

  20 N
• What happens to the weight of an object when it is in free fall?

  The weight remains constant throughout the fall
• What is Newton's first law of motion?

  An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a net external force
• What is inertia?

  The tendency of an object to resist changes in its state of motion
• What is the difference between mass and weight?

  Mass is the amount of matter in an object, while weight is the force of gravity acting on that mass
• What are the units of mass and weight?

  Mass is measured in kilograms (kg) and weight in newtons (N)
• How do you calculate weight?

  Weight = mass × gravitational field strength
• Why does a skydiver's weight remain constant during the fall?

  Because weight is determined by mass and gravitational force, which do not change
• What happens to the resultant force when a skydiver opens her parachute?

  The air resistance increases, leading to a smaller resultant force and a decrease in acceleration
• What happens to kinetic energy when the speed of an object is doubled?

  The kinetic energy quadruples
• How does the design of a building affect its ability to withstand forces?

  Stronger materials and better anchoring increase resistance to damage
• Describe the action-reaction forces when a ball is released on a frictionless surface due to gravity.

  The ball exerts a downward force on the Earth, and the Earth exerts an equal and opposite force on the ball
• What is Newton's second law of motion?

  The force acting on an object is equal to the mass of that object multiplied by its acceleration
• If a car has a mass of 1500 kg and needs an acceleration of 4 m/s², what force is required?

  6000 N
• What is the total inertial mass of a bicycle and rider if a force of 100 N produces an acceleration of 2 m/s²?

  50 kg
• What is momentum?

  Momentum is the product of an object's mass and its velocity
• How does a high-speed car crash differ from a low-speed crash in terms of energy?

  A high-speed crash involves significantly more kinetic energy, leading to greater damage
• What is the effect of doubling the speed of a car on its kinetic energy?

  It quadruples the kinetic energy
• What are the key design aspects that improve a building's resistance to forces?

  • Stronger materials
  • Increased cross-sectional area
  • Better anchoring
  • Improved bracing
• What are the effects of a large lorry hitting a small car compared to a small car hitting a lorry?

  • A large lorry hitting a small car causes more damage.
  • A fast car hitting a wall causes more damage than a slow car.
  • A car hitting a wall causes more damage than hitting a crash barrier.
• What happens to the kinetic energy of a car when its speed is halved?

  • The kinetic energy is reduced to a quarter.
• What is the relationship between mass and weight on different planets?

  • Mass remains constant regardless of location.
  • Weight changes depending on the gravitational field strength of the planet.
• What are the effects of air resistance on a skydiver during free fall?

  • Initially, air resistance is smaller than weight, causing acceleration.
  • As speed increases, air resistance increases until it balances weight, resulting in constant speed.
• What is the significance of action-reaction pairs in collisions?

  • Both objects exert equal and opposite forces on each other.
  • The effects of these forces can differ based on the mass and structure of the objects involved.